Video compression using scalable techniques in the sense used herein allows a digital video signal to be represented in the form of multiple layers and/or in multiple views for multiview environments such as stereoscopic view environments. Henceforth, the described are only multiple layers, with the understanding that with respect to the disclosed subject matter, multiple views can in many cases substitute for multiple layers. Scalable video coding techniques have been proposed and/or standardized since at least 1993.
ITU-T Rec. H.265, entitled High Efficiency Video Coding, version April 2013, (available from International Telecommunication Union (ITU), Place des Nations, 1211 Geneva 20, Switzerland, and incorporated herein by reference in its entirety), is referred herein as HEVC. HEVC may be enhanced by a scalable extension known as SHVC (see JCT-VC-O1008, available from http://phenix.it-sudparis.eu/jct/doc_end_user/current_document.php?id=8527, incorporated herein in its entirety.) SHVC, in contrast to HEVC. may include the feature of coding multiple spatial or SNR enhancement layers in addition to a base layer in one scalable bitstream. Other extensions to H.265 may cover the multiview case.
In SHVC, the layer functionality has, as of the time of this writing, focused on traditional use cases for scalability, such as support for a heterogeneous receiver/decoder population utilizing the same scalable bitstream, or error resilience.
JCT-VC-O0358, entitled “Proposal for Supporting Optional Overlays with MV-HEVC”, available from http://phenix.it-sudparis.eu/jct/doc_end_user/current_document.php?id=8500 and incorporated herein by reference in its entirety, discloses certain techniques to enable overlays using the multiview extension known as MV-HEVC. These techniques can have certain limitations; for example, they are described as being limited to MV-HEVC, support only a single overlay picture, and require an overlay layout for each overlay picture (in contrast to allowing for a single overlay layout for multiple overlay pictures).
It would be advantageous if the aforementioned shortcomings could be avoided.